Contaminated (or spent) acids streams are generated by a number of important industrial processes. For economic and environmental reasons, it is desirable to regenerate these contaminated acids so that they may be reused rather than discarded. One method of regenerating acids to remove contaminants is distillation. While generally effective, distillation methods require high temperatures and special materials to withstand the conditions required to boil acids. The combined cost of the distillation equipment and the high energy requirements make distillation a less attractive alternative for some industries. Another regeneration method involves cooling the contaminated acid to promote precipitation of the contaminants. Such a method is used by the metal pickling industry to regenerate contaminated sulfuric acid. During the metal pickling process, sulfuric acid becomes contaminated with metals and organic fluids. The common practice is to cool the sulfuric acid from its operating temperature, about 330.degree. K., to 273.degree. K. At this lower temperature, the solubility of the metals is lower and some of the contaminants precipitate out. Once the contaminants are separated from the acid, the acid bath is returned to its normal operating temperature. This process extends the life of the acid bath and minimizes the cost of neutralizing the acid prior to disposal. However, this process is not as effective in removing contaminants as the distillation processes. Thus, it would be an advantage to have a regeneration process having a greater ability to remove contaminants without involving distillation.